1. Field of the Invention
The present invention relates to a motion picture camera, television camera lenses and the like, and particularly, to zoom lenses.
2. Description of the Prior Art
Many zoom lenses are constructed for use with a motion picture camera, a television camera and the like. Generally, such zoom lenses include a focusing lens group, zoom optics composed of a variable magnification lens group and a compensation lens group for compensating the change of the focal point due to the magnification variation and a relay lens group. Conventional zoom lenses compensate for the change of the focal point that occurs when the focal distance is changed. The above compensation lens group fails to compensate for the change in the picture angle that accompanies the movement of the focusing lens group when the focal distance is kept constant. Consequently, when a focusing operating is carried out during continuous photography with a motion picture camera, a television camera and the like, the change in the picture angle along with the change of the focal distance is significant during projection or reproduction. Hence, the size of the image remarkably changes out-of-focus, which gives a strange feeling to the observers. This problem is important in a camera having an automatic focus adjusting device. The reason is that the above-mentioned shortcoming is exaggerated because a quick response for the focusing operation is needed in a camera having an automatic focus adjusting device.